Under-center toggle latch



March 31, 19-64 E. G. GRIFFITHS ETAL 3,127,205

UNDER-CENTER TOGGLE LATCH Filed April 17. 1961 3 Sheets-Sheet 1 F I G 5 P 4 fi INVENTORS. EDWARD G. GRIFFITHS w NORMAN s. JOHNSON HEIR ATTORNEY.

March 31, 1964 Filed April 1'7. 1961 E. s. GRIFFITHS EI'AL 3,127,205

UNDER-CENTER TOGGLE LATCH 3 Sheets-Sheet 2 INVENTORS. EDWARD G. GRIFFITHS NORMAN S. JOHNSON T HEIR ATTORNEY.

March 1964 E. G. GRIFFITHS EIAL UNDERQCENTER TOGGLE LATCH 3 Sheets-Sheet 5 Filed April 17, 1961 FIG.

HEIR ATTORNEY.

United States Patent 3,127,205 UNDER-CENTE TOGGLE LATCH Edward George Griffiths, Maywood, and Norman E). Johnson, New Milford, N.J., assignors to Camden Fastener @orporation, Par-amiss, Nah, a corporation of New York Filed Apr. 17, 1961, Ser. No. 115,276 Claims. (Cl. 292-413) This invention relates to toggle latches and relates more particularly to an improved latch fastener having an under-center locking action as distinguished from an overcenter action and wherein all three points that insure continuance of the under-center geometry are built into the operating lever and the tension bar. The foregoing relationship is unaffected by any movement of a fixed keeper carried by a second member to be secured to a first member carrying the latch fastener.

The usual over-center toggle latch such as is shown in Patent No. 2,679,417 has an annoying habit of flying open under certain circumstances. In most instances, two wall members lying in a common plane are to be secured together in abutting relationship. As long as the member carrying the keeper remains in this plane the toggle locking action is preserved. If, however, the second member were to be displaced upwardly from the plane the toggle locking action is destroyed. A similar result is achieved if the members are subjected to a shock or jolt. The reason for this informity is in the fact that one of the three points that control the toggle geometry is the hook element or keeper carried by the second member to be secured and if this member is displaced a distance equal to the over-center distance the toggle advantage is lost. This is because the keeper acts as the stop limiting rotation in a locking direction of the operating lever and if this stop moves, the over-center locking action is lost.

In the improved under-center latch of the present invention the tension bar, with its attaching loop or hook at its outer end, is pivoted at its inner end to the inner end of the operating lever, which latter is pivotally mounted slightly inwardly from its inner end in a bracket fixed on the first member to be secured. A fixed keeper is carried by the second member. When the parts are in fully unlatched position the three critical points controlling the under-center toggle action, i.e., the lever pivot, the levertension bar pivot, and the loop and lock element at the outer end of the tension bar, are generally aligned with each other and with the elongated operating lever. The lock element is now moved into operative engagement with the keeper and the lever is swung through an arc of about 180 degrees, during which movement the connecting pivot between tension bar and lever moves through an under-center arcuate path. This motion continues until the lever contacts the tension bar, which latter acts as a stop for the lever. When this occurs this connecting pivot has reached a position above a straight line connecting the lever pivot and the attaching loop at the outer end of the tension bar. Since the latter is now under tension it creates a rotational moment in the lever in the direction in which it was turning while achieving the locking action. This movement is resisted by the fact that the tension bar forms a stop-limiting further rotation of the lever. Accordingly, if the second member, i.e., the container cover, is displaced from its initial plane, it has no effect whatsoever upon the toggle action because this under-center geometry cannot be destroyed unless, of course, the handle is manually rotated in the opposite direction.

In the drawings:

FIG. 1 is a perspective view of a fastener embodying the present invention and showing a fragmentary view of two members to be secured together thereby;

3,127,205 Patented Mar. 31, 1964 FIG. 2 is a plan view of the fastener with the operating handle in retracted position;

FIG. 3 is a section taken on line 33 of FIG. 2;

FIG. 4 is a section similar to FIG. 3 but showing the parts in fastened position;

FIG. 5 is a schematic illustrating the principle of operation of the toggle latch of the present invention;

FIG. 6 is a perspective View showing a modified form of the invention wherein the draw hook is not adjustable as to length;

FIG. 7 is a broken side elevation showing the parts in partially unfastened position;

FIG. 8 is a plan view, partially in section, with the parts in the position of FIG. 6;

FIG. 9 is a perspective view showing a second modified form of the invention with the parts in fastened position;

FIG. 10 is a side elevation thereof;

FIG. 11 is a side elevation showing the parts in unfastenecl position;

FIG. 12 is a plan view of a modified form of adjustable tension bar;

FIG. 13 is a longitudinal section taken through the center thereof.

In the first embodiment of the invention the latch is employed to secure members 10 and 11 together. A sheet metal angle bracket has its base 12 secured to member Iii and an operating handle or primary lever 14 of channeled construction is mounted between side walls 16 of the bracket by spaced, axially aligned pivot pins 17 which pass through aligned holes 18 spaced inwardly a distance from the inner end of the handle. This handle has a central raise/d section 19 at its outer end to facilitate raising the same when the parts are in the locked position of FTG. 4 and also to space it from the surface of a member 12 when the parts are unlocked and the handle is in the rearward position of FIG. 3.

The drawhook-tension bar assembly includes a hook section 2d and a threaded rear terminal or shank section 21 which may be formed from sheet metal in a single piece. The drawhook is mounted in a tension bar element which may also be formed from a single elongated blank bent double and providing at its center a hinge pin loop 22 and overlapping flanges 24 which may be welded together and provided with complementary outwardly curved radial sections 26 forming an opening which is internally threaded to receive the shank of the drawhook in readily adjustable relation. This threaded sleeve section has slots 28 to indicate the position of the threaded shank section 21 of the drawhook. The pivot element is mounted on a pivot pin 29 positioned in aligned openings at the inner end of side walls 30 of the primary lever.

The drawhook at the outer end of the tension bar engages a hook shaped keeper 31 mounted on the second member 11 and in order to secure a tight closure between the parts of the drawhook it is first adjusted to a position where it draws the meeting faces of the members firmly together during the last increment of rotation of the handle or primary lever. In the open position of FIG. 3, the experienced user will easily gauge an approximate setting due to his knowledge of the usual travel of the hook section 20 from the open to the closed position of FIG. 4.

When in this fully opened position of FIG. 3 the major axes of the operating handle and the pivot elements are generally aligned. While the keeper 31 on the second member 11 acts as a stop limiting rotation in a locking direction of the tension bar it is the tension bar itself which limits rotation of the operating handle. When the handle reaches the locked position of FIG. 4 the pivot pin 29 has passed just beyond (i.e., upwardly) of a straight line between the axis of pivot 17 and the central point of attachment between hooks 2i and 31. It will be seen from an examination of FIG. 4 that any displacement upwardly or downwardly of second member 11 and the keeper 31 does not destroy the integrity of this toggle or below-center relationship since the drawhook and the handle must travel conjointly, i.e., as a unit, when moved due to any vertical displacement of the keeper.

During this movement of the operating handle through an arc of about 180 the inner end of said handle with pivot 29 travels under center and upwardly past a straight line drawn betweenhook 2t) and pivot 17. The parts are so proportioned that when a desired measure of toggle locking action has been achieved, handle 14 has contacted the tension bar which acts as a stop for the handle and since pivot 29 is now above center the parts can rotate on pivot 17 and always maintain the toggle relationship. The relationship between the parts, and the principle of operation, is shown to good advantage in the schematic showing of FIG. 5. The load W acting in the direction shown induces a tensile load on the drawhook or tension bar. The drawhook tensile load is transmitted to handle H through pivot A. This force will rotate handle about pivot B in direction shown. The handle stops rotating when point P of handle meets the top of tension bar. The resulting distance (moment arm) will remain constant throughout any movement of the load W.

In the modified latch of FIGS. 68 the tension member or drawback 36 is not positively adjustable as to length but it has an arched, spring construction which deflects, and therefore elongates when it is placed under tension. It is stamped out from a single piece of sheet metal and has a loop 38 for a hinge pin 39 at one end and a book 40 at the other end. FIG. 7 shows the outwardly arched contour at 41 starting at a point roughly one-third the distance outwardly from the pivot loop. As the latch is drawn to fastened position, this arched section has a tendency to straighten and hence to increase its effective length. This ability to straighten can be reduced by forming a plurality of longitudinal ribs shown at 42 in FIGS. 6 and 8, but not in FIG. 7.

An operating handle 44 of channeled construction is stamped from sheet metal and has side flanges 4d and ribs 48. The flanges on the handle are provided at their inner ends with aligned openings 49 to receive pivot pin 39 for the tension bar and the handle is itself pivotally mounted by means of pivots 59 in the opposed side walls 51 of a mounting bracket 52. It will be noted from FIG. 8 that the openings 54 for pivots 50 are spaced inwardly from openings 49 for pivot pin 39.

The pivoted structure in this case is reinforced by oval shaped plates 56 secured to flanges 46 by pins 58. Bracket 52 is secured to one member 6%) which is formed with a tongue and the other member 62 to be secured is formed with a groove 64 to receive the tongue. This member also has an abutment 66 to receive hook 49.

It will be noted that in each of the embodiments described thus far, when the handle is in the fully retracted position of FIG. 3 the tension bar may be stored entirely within this channelled member and with no increase in the overall dimensions of the envelope.

Substantially the same arrangement is shown in the second modified form of FIGS. 9, l and 11, wherein the tension bar 743 is formed with side walls '71 and with a hook 72 at its outer end and this outer section has strengthening fins 73. At its inner end it is pivotally mounted at 74 to operating handle 75 which is provided with side flanges 76 and which are arranged to move inside of side walls 71 of the tension bar. At the outer end of this handle there is a pair of upwardly curved finger portions 78 and the operating handle is mounted on a pair of aligned pivot pins 80 which pass through openings spaced inwardly from pivot member 74. and downwardly therefrom when viewed as in FIG. 10. These pivot pins are mounted in side walls 81 of a mounting bracket 82. When the tension bar and the handle are in a fully retracted position the latter is stored within the tension bar.

In FIGS. 12 and 13 a modified adjustable tension bar is shown. The inner or hub section 88 is made like the one in FIGS. 2 and 3 with pivot loop 89. It has superimposed, welded sections 90 forming an opening 91 which in this case is unthreaded and which receives a threaded shank 92 to which a hook (not shown) is welded. A round nut 95 is received on the shank in an opening 97. By having the nut of a diameter no greater than the thickness of the loop section it has infinite adjustability. A spring 99 urges the shank outwardly.

While there have been described herein what are at present considered preferred embodiments of the invention, it will be obvious to those skilled in the art that many modifications and changes may be made therein without departing from the essence of the invention. It is therefore to be understood that the exemplary embodiments are illustrative and not restrictive of the invention, the scope of which is defined in the appended claims, and that all modifications that come within the meaning and ranges of equivalency of the claims are intended to be included therein.

What we claim is:

1. An under-center toggle latch for joining two members in assembled relationship including in combination an engageable element on one of said members, a bracket having a base carried by the other of said members, an operating lever, means comprising a fixed pivot for mounting said lever on said bracket at a location intermediate the lever ends and at a position on said bracket above said base, a drawbar having means thereon for engaging said element and means comprising a movable pivot connecting said drawbar to said lever adjacent one end thereof whereby the other lever end forms a handle, the shortest distance between said fixed pivot and said other member being greater than the distance between said fixed pivot and said movable pivot, said handle being adapted to be operated to swing said movable pivot through the space between said base and said fixed pivot to draw said bar into engagement with said element.

2. An under-center toggle latch for joining two members in assembled relationship including in combination an engageable element on one of said members, a bracket having a base carried by the other of said members, an operating lever, means comprising a fixed pivot for mounting said lever on said bracket at a location intermediate the lever ends and at a position on said bracket above said base, a drawbar having means thereon for engaging said element, means comprising a movable pivot connecting said drawbar to said lever adjacent one end thereof whereby the other lever end forms a handle, the shortest distance between said fixed pivot and said other member being greater than the distance between said fixed pivot and said movable pivot, said handle being adapted to be operated to swing said movable pivot through the space between said base and said fixed pivot to draw said bar into engagement with said element and means for adjusting the length of said drawbar.

3. An under-center toggle latch for joining two members in assembled relationship including in combination an engageable element on one of said members, a bracket having a base carried by the other of said members, an operating lever, means comprising a fixed pivot for mounting said lever on said bracket at a location intermediate the lever ends and at a position on said bracket above said base, a drawbar having means thereon for engaging said element and means comprising a movable pivot connecting said drawbar to said lever adjacent one end thereof whereby the other lever end forms a handle, the shortest distance between said fixed pivot and said other mem-, ber being greater than the distance between said fixed pivot and said movable pivot, said handle being adapted to be operated to swing said movable pivot through the space between said base and said fixed pivot to draw said bar into engagement with said element, said drawbar forming a stop for said handle after said handle is operated.

4. An under-center toggle latch for joining two members in assembled relationship including in combination an engageable element on one of said members, a bracket having a base carried by the other of said members, an operating lever, means comprising a fixed pivot for mounting said lever on said bracket at a location intermediate the lever ends and at a position on said bracket above said base, a resilient drawbar having means thereon for engaging said element and means comprising a movable pivot connecting said drawbar to said lever adjacent one end thereof whereby the other lever end forms a handle, the shortest distance between said fixed pivot and said other member being greater than the distance between said fixed pivot and said movable pivot, said handle being adapted to be operated to swing said movable pivot through the space between said base and said fixed pivot to draw said bar into engagement with said element.

5. An under-center toggle latch for joining two members having walls in assembled relationship including in combination an engageable element on the outside of one of said walls, a bracket having a base, means mounting said bracket on the outside of the other wall, an operat ing lever, means comprising a fixed pivot for mounting said lever on said bracket at a location intermediate the lever ends and at a position on said bracket above said base, a drawbar having means thereon for engaging said element and means comprising a movable pivot connecting said drawbar to said lever adjacent one end thereof whereby the other lever end forms a handle, the shortest distance between said fixed pivot and said other wall being greater than the distance between said fixed pivot and said movable pivot, said handle being adapted to be operated to swing said movable pivot through the space between said base and said fixed pivot to draw said bar into engagement with said element.

References Cited in the file of this patent UNITED STATES PATENTS 1,346,655 Jenkins July 13, 1920 1,647,938 Seguin Nov. 1, 1927 1,691,833 Vosburg Nov. 13, 1928 2,704,218 Claud-Mantle Mar. 15, 1955 2,712,955 Andrews July 12, 1955 2,904,141 Henrichs Sept. 15, 1959 FOREIGN PATENTS 330,348 Switzerland July 15, 1958 

1. AN UNDER-CENTER TOGGLE LATCH FOR JOINING TWO MEMBERS IN ASSEMBLED RELATIONSHIP INCLUDING IN COMBINATION AN ENGAGEABLE ELEMENT ON ONE OF SAID MEMBERS, A BRACKET HAVING A BASE CARRIED BY THE OTHER OF SAID MEMBERS, AN OPERATING LEVER, MEANS COMPRISING A FIXED PIVOT FOR MOUNTING SAID LEVER ON SAID BRACKET AT A LOCATION INTERMEDIATE THE LEVER ENDS AND AT A POSITION ON SAID BRACKET ABOVE SAID BASE, A DRAWBAR HAVING MEANS THEREON FOR ENGAGING SAID ELEMENT AND MEANS COMPRISING A MOVABLE PIVOT CONNECTING SAID DRAWBAR TO SAID LEVER ADJACENT ONE END THEREOF WHEREBY THE OTHER LEVER END FORMS A HANDLE, THE SHORTEST DISTANCE BETWEEN SAID FIXED PIVOT AND SAID OTHER MEMBER BEING GREATER THAN THE DISTANCE BETWEEN SAID FIXED PIVOT AND SAID MOVABLE PIVOT, SAID HANDLE BEING ADAPTED TO BE OPERATED TO SWING SAID MOVABLE PIVOT THROUGH THE SPACE BETWEEN SAID BASE AND SAID FIXED PIVOT TO DRAW SAID BAR INTO ENGAGEMENT WITH SAID ELEMENT. 